Successive spin reorientation and magnetostriction in (Er1-x Tbx)2Fe14B

Magnetostriction measurements in highly-oriented melt-spun ribbons of (Er_1-xTb_x)₂Fe₁₄B with 0⩽x⩽0.45 have been performed in order to investigate the lattice deformation at the spin reorientation (SR) transitions. The c-axis of the tetragonal cell was found to be aligned perpendicular to the ribbon plane. The sum of the longitudinal and transverse magnetostriction λ_{//+λ⊥, with fields applied within the ribbon plane, was a maximum at successive SR temperatures. A model calculation of the volume change ΔV/V was made by assuming that only the lowest order crystalline electric field potentials at Er and Tb sites affect the volume change. This calculation showed that ΔV/V exhibits a sharp peak at the SR temperatures, which is in accordance with the experimental peaks of λ//+λ ⊥}